For programming documentation, use guillemet double for ". Do not use guillemet droit as this could be interpreted as a single quote '. There is no other ASCII character that could be called a guillemet double, but there are other Unicode characters: “ and ” (opening and closing double quotes, not found on keyboards but automatically inserted when you press " in some word processing software) and « and » (opening and closing French quotes, found on Canadian French keyboards). It's unlikely that programmers would think of anything but " for guillemet double, but if you need to reinforce the choice of character, you can say guillemet droit double or guillemet double symétrique, and explain how to type it.

Don't use the English word quote. Not every French programmer would understand the word.

The easiest solution is probably to use "guillemets droits". Of course, you'll want to show the actual character where you define it. See for example the PHP documentation (where they use guillemets doubles, which seems rather common).